A printed circuit board (PCB) is an important electric part, and is used to provide circuit connections to electric parts and components. A PCB assembly (PCBA) refers to assembly of various electric components on a circuit board by using a surface packaging process, to form a modular product, which is provided to a customer. By means of soldering, the customer client solders the modular product to a main board. For a modular product having a relatively high reliability requirement, to improve the reliability of the modular product, before production is complete, adhesive dispensing usually needs to be performed on some components inside the modular product by using a packaging-level underfill material, so as to increase the reliability of solder joints of the components, and produce a particular moisture-proof effect for the components.
A material for adhesive dispensing is usually resin, and an adhesive dispensing operation is usually performed before a shielding cover is mounted. For a second-reflow modular product (that is, a modular product that needs to be assembled on a main board by using a surface mount and soldering technology) having a high reliability requirement, after the shielding cover is mounted, second-reflow soldering processing needs to be performed. Therefore, an adhesive dispensing operation is also performed before second reflow soldering. It is well known that a process of second-reflow soldering processing is usually accompanied with high-temperature processing (for example, a temperature higher than 250 degrees Celsius (° C.)). At a high temperature, soldering tin enveloped by resin melts, and molten soldering tin flows inside a chip to cause a short circuit inside the chip, causing a function of a product to fail.
To resolve the foregoing problem, a solution is to perform an adhesive dispensing operation after second-reflow soldering processing. However, second-reflow soldering processing is required to be performed after a shielding cover is mounted. Therefore, how to implement that an adhesive dispensing operation can still be performed after a shielding cover is mounted becomes a key to the resolution of the foregoing problem.